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TITLE:
PHP HTTP Chunked Encoding Processing Signedness Vulnerability

SECUNIA ADVISORY ID:
SA39573

VERIFY ADVISORY:
http://secunia.com/advisories/39573/

DESCRIPTION:
Stefan Esser has discovered a vulnerability in PHP, which can be
exploited by malicious people to cause a DoS (Denial of Service).

The vulnerability is caused due to a signedness error within the
"php_dechunk()" function in ext/standard/filters.c when processing
HTTP streams. This can be exploited to corrupt memory and cause a
crash when an HTTP chunk having an overly large size is processed
through the "dechunk" filter.

The vulnerability is confirmed in version 5.3.2. Other versions may
also be affected.

SOLUTION:
Do not process untrusted HTTP streams in PHP applications.

PROVIDED AND/OR DISCOVERED BY:
Stefan Esser

ORIGINAL ADVISORY:
http://php-security.org/2010/05/02/mops-2010-003-php-dechunk-filter-signed-comparison-vulnerability/index.html

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